# ① 创建字典
course_dict = {
    "吕红": "数据库",
    "周婷": "线性代数",
    "肖扬": "Python",
    "李娟": "数据库",
    "丁锦": "英语",
    "周玲玲": "Java"
}
print("初始字典：", course_dict)

# ② 增加赵红讲授Java的信息
course_dict["赵红"] = "Java"
print("增加赵红后：", course_dict)

# ③ 周玲玲改为讲授Python
course_dict["周玲玲"] = "Python"
print("周玲玲改授Python后：", course_dict)

# ④ 删除周婷授课信息
if "周婷" in course_dict:
    del course_dict["周婷"]
print("删除周婷后：", course_dict)

# ⑤ 遍历字典
print("所有教师及课程：")
for teacher, course in course_dict.items():
    print(f"{teacher}讲授{course}")

print("讲授Python的教师：")
for teacher, course in course_dict.items():
    if course == "Python":
        print(teacher)